Unable to establish link between FG6501F and Cisco ACI Leaf switch

We have two FG6501F firewalls that we plan to upgrade to. We are testing our fiber cables to ensure we have link, prior to deployment.  When connecting the QSFP28 100G fiber cables between the two FG6501F chassis we get link.  However, when connecting from the 100G port on the new Firewall to a 100G port on a Cisco Leaf switch (In Cisco ACI) we do not get link.  Has anyone experienced a similar issue?  Any assistance is appreciated in resolving the issue.